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The surface structure of alpha -Fe (sub 2) O (sub 3) (001) by scanning tunneling microscopy; implications for interfacial electron transfer reactions

Carrick M. Eggleston
The surface structure of alpha -Fe (sub 2) O (sub 3) (001) by scanning tunneling microscopy; implications for interfacial electron transfer reactions
American Mineralogist (August 1999) 84 (7-8): 1061-1070

Abstract

STM images of hematite (alpha -Fe (sub 2) O (sub 3) ) (001) surfaces taken under a wider variety of conditions than in previous studies are presented. The results strongly suggest that only Fe sites contribute to the tunneling current. Specifically, corrugated unit-cell structures expected of the Fe sublattice are observed under both occupied- and unoccupied-states imaging conditions. A pattern of apparent vacancies was observed under conditions previously attributed to oxygen states; this is most simply interpreted either as Fe vacancies, or Fe sites whose electronic structure has been altered by a (unknown) coordinating anion, but difficult to explain as the oxygen sublattice. For unoccupied states imaging, decreasing the tip-sample distance (increasing the tunneling current) results in an image change from only one site per unit cell to three sites per unit cell. This is also relatively easy to explain using the Fe sublattice, but difficult to explain using the oxygen sublattice. These results are modeled using resonant tunneling theory, which shows that changes in bias voltage, tunneling medium, and tip-sample distance can have the observed effects only if Fe atoms are being imaged. The results have implications for modeling electron transfer across mineral-water interfaces more generally because they provide a framework for understanding site-specific electron transfer kinetic parameters.


ISSN: 0003-004X
EISSN: 1945-3027
Coden: AMMIAY
Serial Title: American Mineralogist
Serial Volume: 84
Serial Issue: 7-8
Title: The surface structure of alpha -Fe (sub 2) O (sub 3) (001) by scanning tunneling microscopy; implications for interfacial electron transfer reactions
Affiliation: University of Wyoming, Department of Geology and Geophysics, Laramie, WY, United States
Pages: 1061-1070
Published: 199908
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 56
Accession Number: 1999-066012
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 199922
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